Improvement in valves for steam-engines



E. COPE &'J. R. MAXWELL. Valves for Steam-Engines,

No. 200,855. Patented March 5,1878.

NAPETERS, PHOTO-UTHOGRAPHER, WASHINGTON D C .STATES PATENT OFFICE.

EZ'RA'OOPE,OF'HAMILTON, AND JAMES R. MAXWELL, OF CINCINNATI, OHIO.

IMPROVEMENT-IN l/ALVES FOR STEAM-ENGINES.

Specificationforming part of Lettersflatent-No. 200,855, dated March 5,1878; application led July l2, 1877.

To all whom it .ma/.l1 concern.:

.Be it known)l that werEZRA city of.Hamil ton,. county of Butler, andJAMES R. MAxwELL, of the city of ACincinnati,county of Hamilton, andState of Ohiohave invented certain newand useful Improvements inValvesfor Steam-Engines; and we declare thatI the following is a full, clear,and exact description thereof, reference being had to the accompanyingdrawing, which forms a part of this specication.

The object of our invention is to so control the distribution of steamto a steam-engine that it will automatically adjust itself to the Workto be done, causing the piston to make its strokes in equal times, andrendering the engine absolutelyr safe under any variation of load towhich it may be subjected.

The principle and general arrangement herein involved is covered by thepatent to James R. Maxwell, No. 180,433, dated August l, 1876.

We accomplish the above object by the use of a main valve operatedindependently of the main engine by an auxiliary piston and cylinder, orby any other means preferred, and by a movable valve-seat connected tothe main piston by suitable intervening mechanism, and operated by it,moving under the main valve in a direction tending to cut off steam fromthe main cylinder. The motion of the main valve may be controlled by acataract, causing it to make its stroke in either direction in uniformtimes. In cases where the auxiliary cylinder is placed outside thesteam-chest, the auxiliary piston may be moved by water-pressure, andits motion thus controlled without the y use of a cataract; or cocks orplugs may be placed in the exhaust from the auxiliary cylinder, and themotion of the valve thus controlled.

The drawing illustrates an arrangement of the parts suitable forpractical operation, and of simple and convenient construction. Thedetails may be varied in many particulars by one skilled in the artwithout departing from the features covered by this specification.

In the drawing, A indicates the steam-cylinder; B, the piston, and C thesteam-chest. D is the main valve-a plain slide-valve operatedindependently of the main engine, in this case by the auxiliary pistonD', and sliding upon the movable valve-seat. C' is an com', ,of ui@auxiliary cylinder in which the auxiliary piston D operates. Theauxiliary cylinder is cast with or otherwise securedto the movable.valve-seat. Together they are operated from the main piston by means ofthe arm J, lever I', and link I. Portsa a' b are formed in the movableseat. The valve-seat may be'entirel y independent of the auxiliarycylinder, the latter being placed in any other convenient position andthe scat connected directly to the mainpiston. The arrangement shownbrings all the parts compactly together, and may be wholly covered by asingle steam-chest.

The auxiliary valve F is a double D-valve, united by the rod F. Thevalve has no motion of its own, but is carried with the auxiliarycylinder until it is brought into contact with one of the studs F. Thevalve will then pause while the auxiliary cylindermoves under it,changing the commimication of the ports and reversing the stroke of theauxiliary piston D. Any other style of valve may be used, and it may beoperated by contact of the lever I with tappets on its rod, as shown inthe patent of Maxwell before mentioned, or in anyother convenientmanner.

The operation is as follows: In the drawing the piston is shown at theend of its stroke to the right, having carried the valve-seat under themain valve and cut oif steam from the main cylinder. At the same timethe auxiliary cylinder is carried under the auxiliary valve F, admittingsteam to the right end of the auxiliary cylinder and exhausting from itsleft end. The auxiliary piston, therefore, moves to the left at thevelocity permitted by the iow of liquid in the cataract-cylinder,carrying the main valve with it, opening the port A' on the right, andadmitting steam to the right end of the main cylinder. The main piston Bthen commences its stroke to the left. The main piston, through thelever I, commences to move the movable seat to the left-the samedirection in which the main valve is moving. If the load upon the mainpiston continues uniform, its velocity will be uniform during its entirestroke, and the auxiliary piston will travel just in advance of themovable seat at a constant velocity, controlled by the cataract,admitting an equal supply of steam to the cylinder during the entiretravel of the piston. If the load upon the main piston should belessened, its velocity would be accelerated; and hence the movable seat,traveling more rapidly than the valve, will be carried under it, nearlyor quite cutting o' the admission of steam. The piston will then come torest until the main valve, which continues to travel, again uncovers theport, admitting sufficient steam to carry the main piston to the end ofits stroke at its normal velocity. Should the load upon the piston beincreased, the velocity of the piston will be re- Y tarded, causing themovable seat to advance more slowly than the main valve. Hence thesteam-ports will be opened Wider, admitting a greater supply of steam tothe cylinder. Should the velocity of the piston be greatly accelerated,the movable seat would be carried under the main valve far enough toadmit steam in advance of the piston and reverse its stroke.

It will thus be seen that the engine is selfgoverning, the supply ofsteam admitted being properly proportioned to the amount of Work to bedone. Bya simple change of mechanism the engine may be placed whollyunder the control of the engineer, enabling him to regulate the time ofthe stroke, as well as its velocity and direction.

What We claim as new, and desire to secure by Letters Patent, is-

1. In a steam-engine, the main valve D, operated independently of themain engine, and the movable valveseat, operated from the main piston bya fixed connection of intermediate mechanism, in combination with thecataract H, by means of which the distribution of steam to the maincylinder is varied according to the work to be done, substantially asdescribed.

2. The auxiliary cylinder C', secured to and moving With the movablevalve-seat, in combination with the auxiliary piston D and the mainvalve D, constructed and arranged substantially as and for the purposedescribed.

EZRA COPE. J. R. MAXWELL.

Witnesses:

R. C. MCKINNEY, A. S'roUGHToN.

